Stock values for social gaming giants DeNA and GREE plummeted over 20% today following a weekend report that the Consumer Affairs Agency will be asking that game makers stop the use of a sales method known as "kompu gacha." According to the report, which first appeared in The Yomiuri Shimbun, the agency believes that this sales method violates certain sales laws.

Kompu Gacha, or "Complete Gacha," is an advanced form of gacha. In traditional gacha, players insert money into vending machines to get a capsule containing a random toy. Many free-to-play social games get revenue from a digital version of this, where the prizes are virtual items.

Complete Gacha requires that players collect a particular set of items through the standard gacha games in order to obtain rare "grand prize" items. According to the Yomiuri report, kompu gacha games have become the main revenue source for operators of SNS gaming services.

Bloomberg received confirmation today from Consumer Affairs Agency representative that investigations into the legality of the kompu gacha sales method are under way and that a formal statement will be issued soon.

Tokai Tokyo Securities market analyst Makoto Sengoku warned Bloomberg that if kompu gacha sales tactics are regulated, social game makers will see a pillar of their earnings crumble.